This invention relates to a raw mixed sugar juice clarification apparatus that allows precipitation, subsidation and separation of insoluble and mud particles in raw mixed sugar juice in a more efficient way than that which is presently practiced in the international sugar industry.
Physical and chemical clarification of raw mixed sugar juice is currently practiced in the sugar industry by the addition of lime and sometimes, additional substances that cause a precipitate to form within the raw mixed sugar juice. This precipitate, sometimes including a polyelectrolyte flocculant, entraps suspended impurities in the raw mixed sugar juice. Due to the difference in densities between the precipitate and the clear sugar juice; the precipitate sinks to the lower region of the conventional clarifiers used in the industry. The clear sugar juice, due to its lower density; rises to take-off points in the upper section of conventional clarifiers.
Whilst there are various clarifier designs currently being used in the industry; they all have a common operational disadvantage. This is that the raw mixed sugar juice requires even and gentle distribution into the clarifier body together with an equally even and gentle extraction of the clear sugar juice and precipitate in order to permit vertical rising of the clear sugar juice and vertical settlement of the precipitate in a turbulence-free environment.
This condition of turbulence-free vertical ‘plug flow’ is practically impossible to achieve with the current designs of fixed, multi-point inlet and outlet facilities for the incoming raw mixed sugar juice and outgoing clear sugar juice and precipitate. Pure ‘plug flow’ would necessitate an infinite number of inlet and outlet facilities spread over the entire cross section plan of the clarifier vessel. Conventional clarifiers consequently operate on a compromise between vertical plug-flow and horizontal flow, which is necessary in order to distribute and extract the juice and precipitate, into and out of the clarifier body. The turbulence caused by the interaction of vertical and horizontal flow patterns results in flow short-circuiting and semi-stagnant zones within the contents of the clarifier. Flow short-circuiting and semi-stagnant zones produce a variation in the residence time of the sugar juice in the clarifier. This turbulent condition also affects the gravitational rate of settlement of the precipitate thus requiring a larger volume for settlement than a volume free from turbulence. A larger volume clarifier results in a longer average retention time for sugar juice in the clarifier. Sugar juice degrades with time and a loss of sucrose through inversion takes place, therefore the shortest retention time of sugar juice in a clarifier is a distinct production advantage.